DDM, Unpredictable behavior (Command Line), three U2414H, KVM switch

Question

I have a a triple monitor setup (three U2414H) connected to both my work laptop and my home PC. These monitors have HDMI/HDMI/DP/mDP inputs. The center monitor is controlled by a KVM switch. The far left monitor is the monitor I intend to use DDM for, in order to control input switching. The plan was to assign a shortcut hotkey to a bat file using DDM command line parameters and control input switching from my keyboard the same way I do with the KVM monitor. The left monitor is identified as Monitor 1 for both PC and laptop. The right monitor is always and only connected to my PC. I have my PC connected to HDMI 1 and my work laptop to HDMI 2 on the left monitor. I created a bat file on both computers with the following command on my pc: >>ddm.exe/1:setactiveinput hdmi2 and  the following command on my laptop: >>ddm.exe/1:setactiveinput hdmi1 It works very inconsistently. Maybe only 10% of the time. I think the main issue is that the assignment numbers for the monitors seem to change randomly. I understand re-scan lag and that it takes a minute when inputs are switched; but even after a substantial amount of time, the monitor input assignment still seems inconsistent. Sometimes when I run the command, it switches the right hand monitor input, other times the center monitor input. And then in the same session, it seems to readjust and switch the assignment back to the way I expected and then works again. I’m just trying to find a consistent workable solution. Is there a way to configure DDM to only work with a single monitor? I really have no use for the application besides input switching which I only need for one monitor. Or is there a better way to achieve what I am trying to accomplish? Thanks in advance

swamped207 · Answer

The easiest way to configure DDM to work with only one of your 3 monitors is to simply turn DDC/CI off on the other two via each monitor's OSD.

As for the rest, DDM numbers monitors in the order Windows enumerates them, so you are s not possible in the current version, but it could be easily added in future.

One last thing worth mentioning: with your U2414s, you can only change the active input over the active input. If your PC is connected to HDMI1 and your laptop is connected to HDMI2, and the PC/HDMI1 input is active, you can only change to the laptop/HDMI2 from DDM running on the PC/HDMI1. You can't do it from DDM running on the laptop/HDMI2. Put another way, you cannot make an inactive input active over an inactive input - to do that you need newer ~2017 model year Dell monitors...

AkinJ · Answer

swamped207, thanks a lot. Though not ideal, disablng DDC/CI on the center and right monitor seems to work better. Still takes a while to recognize the single monitor and other times the setactiveinput command is non-responsive. Doesn't switch as smoothly as a kvm switch but that's understandable. The only reason disabling DDC is non ideal is due to lost ability to control the monitors via my graphics card software (I'm no a fan of u2414h touch controls).

Really hope the ability to identify monitors via a hardware number is implemented in the future

Yes I'm aware that inputs can be switched only from the active source and that's the only way I plan on doing it.

swamped207 · Answer

Try this: restart DDM on both the desktop PC and the laptop, and then every minute or so change the active input until you get a failure. When you get a failure, immediately generate a diagnostic report on both the PC and the laptop, and post them here - they should indicate why the command failed.

(To generate the log, hold the SHIFT key hold and right-click the DDM system tray icon, then select "Save diagnostic report" from the popup menu.)

Monitors

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